Manufacturing of semiconductor devices typically involves performing a sequence of procedures with respect to a substrate such as a silicon wafer, a glass plate, a mask, a reticule, etc. These steps may include polishing, deposition, etching, photolithography, heat treatment, and so forth. Usually a number of different processing steps may be performed in a single processing system “tool” which includes a plurality of processing chambers. However, it is generally the case that other processes are required to be performed at other processing locations within a fabrication facility, and it is accordingly necessary that substrates be transported within the fabrication facility from one processing location to another. Depending upon the type of semiconductor device to be manufactured, there may be a relatively large number of processing steps required, to be performed at many different processing locations within the fabrication facility.
It is conventional to transport substrates from one processing location to another within substrate carriers such as sealed pods, cassettes, containers and so forth. It is also conventional to employ automated substrate carrier transport devices, such as automatic guided vehicles, overhead transport systems, substrate carrier handling robots, etc., to move substrate carriers from location to location within a fabrication facility or to transfer substrate carriers from or to a substrate carrier transport device.
Previously incorporated U.S. patent application Ser. No. 10/650,310, filed Aug. 28, 2003, entitled “System for Transporting Semiconductor Substrate Carriers”, discloses a substrate carrier transport system that includes a conveyor for substrate carriers that is intended to be constantly in motion during operation of the fabrication facility which it serves. The constantly moving conveyor is intended to facilitate transportation of substrates within the fabrication facility.
Previously incorporated U.S. patent application Ser. No. 10/650,480 filed Aug. 28, 2003, entitled “Substrate Carriers Handler that Unloads Substrate Carriers Directly from a Moving Conveyor”, discloses a high speed substrate carrier transfer station equipped with a substrate carrier handler for unloading substrate carriers from, and loading substrate carriers onto such a substrate carrier transport system. In one embodiment, the substrate carrier transfer station comprises a substrate carrier handler that includes a horizontal guide that is moveable along parallel vertical guides, and an end effector that is moveable horizontally along the horizontal guide. To unload a substrate carrier from a moving conveyor that transports substrate carriers and that passes adjacent to the high speed substrate carrier transfer station, the end effector is moved along the horizontal guide at a velocity that substantially matches that of the substrate carrier (e.g., by substantially matching substrate carrier speed in a horizontal direction). The end effector may also substantially match a position of the substrate carrier while substantially matching a velocity of the substrate carrier. When so matching, the end effector may be raised by moving the horizontal guide upwardly along the vertical guides, so that the end effector contacts and lifts the substrate carrier from the substrate carrier transporter. A substrate carrier may similarly be loaded onto the moving substrate carrier conveyor by substantially matching end effector and conveyor velocities (and/or positions) during loading.
Efficiency gains may be achieved via increasing the common speed of the end effector and the substrate carrier during such transfers, which underscores a need for precise and efficient interaction between separately supported and separately driven portions of the system.